The invention relates to a navigation method for a means of transportation, in particular for a vehicle, motor vehicle, ship or aircraft, for navigating from a starting point to a destination, in which a route from the starting point to the destination is specified and the means of transportation or its user is guided along this route.
Navigation systems permanently installed in means of transportation, such as motor vehicles, aircraft or ships, direct a driver or operator of the means of transportation quickly, simply and safely from a current location to a desired destination without the driver or operator of the means of transportation having to plan a route complicatedly in advance and acquire appropriate map material. To that end, navigation data based for instance on charts, geographic maps, or road maps, are available, stored on something like a digital map base, for instance on CD-ROM. The navigation device uses the Global Positioning System (GPS), for instance, to ascertain an instantaneous location and calculate appropriate navigation instructions that lead to the destination.
In navigating a motor vehicle through a network of roads or streets, for instance, reproduced by a digital map base stored in memory in the navigation system, it happens that a driver will select courses or legs that he prefers, for instance based on his particular knowledge of the location, that deviate from a route specified by the navigation system. This often happens with commuters, for instance, who take a regular route between where they live and where they work. Because such familiarity with places or regular routes is entirely unknown to conventional navigation systems, they keep trying to return the driver to the specified route by instructing him to do so. The driver finds this unpleasant and annoying, however.
Moreover, from conventional, self-sufficient navigation systems that calculate a route based solely on the digital map base, it is impossible to learn that in actuality such external factors as frequent unexpected high traffic density on certain legs at certain times of day result in average speeds different from those stored for that particular partial course in the digital map base. For instance, there may in fact be faster routes that the navigation system cannot find in the digital map base, because of its fixedly specified average speeds.
It is the object of the present invention to present an improved method of the above type which overcomes the aforementioned disadvantages.
To that end, according to the invention it is provided that upon departing from the specified route before reaching the destination, the course traveled at least until re-entering the specified route or reaching the destination is recorded, stored in memory, and upon a later request for a route with the same starting point and destination, the course stored in memory is proposed as the route or the applicable route segment that replaces an originally proposed route segment.
This has the advantage that a navigation system will accordingly learn so-called regular routes that the user or driver of the means of transportation is quite familiar with and prefers, such as courses commuters drive daily, and later immediately proposes them as a specified route or part of a specified route. At the same time, the navigation system optionally learns new roads or streets, if the driver chooses a course over roads or streets that are not yet stored in a digital map base of the navigation system.
Preferable refinements of the method are described in claims 2-6.
Expediently, upon departing from the specified route before reaching the destination, a user is asked to input a confirmation as to whether the course then traveled is a course to be stored in memory and proposed again later, or not. The system accordingly receives the information whether the departure is an intended or a mistake in deviation from the guided route.
Alternatively, upon departing from the specified route before reaching the destination, a user is asked to input a confirmation whether the course subsequently traveled is to be recorded, or not, and upon re-entering the specified route or reaching the destination, a user is asked to input a confirmation whether the recorded course is to be stored in memory as a preferred course, or not.
In a preferred embodiment, on driving again over a course stored in memory, the average speeds attained in each case are detected and stored in memory, and the average speeds stored in memory are averaged over a predetermined or user-specified period of time and compared with average speeds stored in memory in a digital map base for alternative routes or partial routes, and an alternative route or partial route is proposed if the memorized, averaged average speeds are less, by a predetermined or user-specifiable amount, for instance of 30%, than the average speeds stored in memory in the digital map base for an alternative route or partial route.
Also in a method of the above type, it is provided according to the invention that average speeds attained during the guidance along the route or along individual course segments are detected, stored in memory, and compared with average speeds stored in a digital map base for alternative routes or course segments, and upon a later request for a route with the same starting point and destination, an alternative route or course segment is proposed if a detected average speed for a route or course segment is less by a predetermined value than an average speed stored in the digital map base for the corresponding alternative route or course segment.
This has the advantage that by constant monitoring of current traffic situations while a route is being driven, the navigation system can tell for a future route calculation whether a value for the average speed to be expected that is stored in memory in the digital map base for the applicable route or leg is out of date or nonapplicable.
To illuminate incidental statistical deviations in various average speeds, the average speeds detected are averaged over a predetermined number of traversals of a route before a comparison with average speeds stored in the digital map base is made.